Currently being completed and edited by William Bonificio
Brownian motion was identified by Robert Brown in 1827 after looking at the jittery movement of pollen on water. It can be defined as the apparent random motion of particles suspended on a fluid. Although often confused with the term 'random walk' they are two distinct phenomena.
Brownian motion, and the mathematical models that describe it, have been used for over a century to describe a multitude of phenomena. For example, Einstein used Brownian motion to describe both the existence of atoms, and the kinetic model of thermal equilibrium. Among other things, economists have been using Brownian motion since the early 20th century to model the stock market.